EP4195877A1 - Thermoresistive heizplatte für mikrowellengerät - Google Patents

Thermoresistive heizplatte für mikrowellengerät Download PDF

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Publication number
EP4195877A1
EP4195877A1 EP22210948.0A EP22210948A EP4195877A1 EP 4195877 A1 EP4195877 A1 EP 4195877A1 EP 22210948 A EP22210948 A EP 22210948A EP 4195877 A1 EP4195877 A1 EP 4195877A1
Authority
EP
European Patent Office
Prior art keywords
thermo
resistive
heating plate
microwave
substrate
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP22210948.0A
Other languages
English (en)
French (fr)
Inventor
Margherita BASSO
Ping Wu
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Whirlpool Corp
Original Assignee
Whirlpool Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Whirlpool Corp filed Critical Whirlpool Corp
Publication of EP4195877A1 publication Critical patent/EP4195877A1/de
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/64—Heating using microwaves
    • H05B6/647—Aspects related to microwave heating combined with other heating techniques
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24C—DOMESTIC STOVES OR RANGES ; DETAILS OF DOMESTIC STOVES OR RANGES, OF GENERAL APPLICATION
    • F24C7/00—Stoves or ranges heated by electric energy
    • F24C7/06—Arrangement or mounting of electric heating elements
    • F24C7/067—Arrangement or mounting of electric heating elements on ranges
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/64—Heating using microwaves
    • H05B6/6402—Aspects relating to the microwave cavity
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/64—Heating using microwaves
    • H05B6/647—Aspects related to microwave heating combined with other heating techniques
    • H05B6/6491—Aspects related to microwave heating combined with other heating techniques combined with the use of susceptors
    • H05B6/6494—Aspects related to microwave heating combined with other heating techniques combined with the use of susceptors for cooking

Definitions

  • the present application is directed to a cooking appliance, and more particularly a thermo-resistive heating coating in heating appliances which use microwave heating.
  • Ovens are heating appliances for food preparation having a housing defining a cavity forming a cooking chamber therein.
  • Ovens include a heating mechanism for cooking food placed within the cooking chamber, with the heating mechanism being variable across different types of ovens, and two or more types of heating mechanisms may be combined in combination ovens.
  • Common types of ovens include electric ovens (which include conduction/conventional and convection ovens), gas ovens, toaster ovens, and microwave ovens.
  • the heating mechanisms vary across these ovens, with some including the heating mechanisms within the cooking chamber itself (e.g., conventional ovens), or in the housing (e.g., convection ovens) such that energy or heat is transferred to the cooking chamber or the food.
  • the heating mechanism in electric ovens includes electric coils (with circulation via fans in convection ovens) to heat the cooking chamber, in gas ovens includes burning natural gas to heat the cooking chamber, and in microwave ovens includes electromagnetic radiation via strong radio waves from devices such as magnetrons to heat the food itself.
  • Heating appliances known as combination ovens may include one or more of the above mentioned heating mechanisms.
  • a heating appliance includes a housing having interior walls with interior surfaces defining a cooking chamber for heating food, a microwave heating source configured to generate microwave radiation for heating the food, and a thermo-resistive heating plate disposed in an opening defined in an interior wall.
  • the thermo-resistive heating plate has a substrate having an inner surface aligned with the interior surface of the interior wall, and a bottom surface opposite to the inner surface.
  • the thermo-resistive heating plate includes a thermo-resistive coating disposed on the bottom surface configured to generate heat upon application of an electric current such that the heat is transmitted through the substrate to the cooking chamber from the thermo-resistive coating, the microwave heating source, or both, and the substrate is transparent to microwave radiation to allow microwave emission through the substrate.
  • the thermo-resistive heating plate may have a microwave efficiency of 20 to 80%.
  • the thermo-resistive heating plate may further include an insulation layer, with the thermo-resistive coating positioned between the insulation layer and the substrate.
  • the insulation layer may be a ceramic material.
  • the thermo-resistive heating plate may include electrical contacts on the bottom surface to connect the thermo-resistive coating to a power supply. In certain further embodiments, the electrical contacts may be silver.
  • the thermo-resistive coating may include a coating matrix with an active filler dispersed therein.
  • the active filler may include single-walled or multi-walled carbon nanotubes.
  • the coating matrix may be a ceramic phosphate material.
  • the active filler may be 0.001 to 30% by weight of the thermo-resistive coating.
  • the thermo-resistive coating may have a thickness of 0.2 nm to 300 microns.
  • the substrate may be a glass-ceramic substrate having a microwave transmittance of 30 to 75%.
  • a heating appliance includes a housing having interior walls with interior surfaces defining a cooking chamber for heating food, a microwave heating source configured to generate microwave radiation for heating the food, and a thermo-resistive heating plate disposed in an opening defined in an interior wall, the thermo-resistive heating plate having a substrate having an inner surface aligned with the interior surface of the interior wall, and a bottom surface opposite to the inner surface.
  • thermo-resistive heating plate also includes a thermo-resistive coating including a coating matrix with an active filler dispersed therein disposed on at least a portion of the bottom surface configured to generate heat upon application of an electric current such that the heat is transmitted through the substrate to the cooking chamber from the thermo-resistive coating, the microwave heating source, or both, and the microwave heating source is positioned in the housing to emit microwave radiation through the substrate.
  • a thermo-resistive coating including a coating matrix with an active filler dispersed therein disposed on at least a portion of the bottom surface configured to generate heat upon application of an electric current such that the heat is transmitted through the substrate to the cooking chamber from the thermo-resistive coating, the microwave heating source, or both, and the microwave heating source is positioned in the housing to emit microwave radiation through the substrate.
  • the interior wall may be a bottom wall or a ceiling defining the cooking chamber.
  • the interior wall may be a side wall defining the cooking chamber.
  • the interior walls may include opposing side walls, and the heating appliance may include a respective thermo-resistive heating plate in each of the opposing side walls defining the cooking chamber.
  • a method of forming a heating appliance includes providing a housing having interior walls with interior surfaces defining a cooking chamber for heating food, applying a thermo-resistive coating to a surface of a substrate to form a thermo-resistive heating plate, and positioning the thermo-resistive heating plate in an opening defined in an interior wall such that microwave radiation can pass through the substrate into the cooking chamber.
  • An inner surface of the substrate, opposite to the bottom surface, is flush with the interior surface of the interior wall to define the cooking chamber.
  • the method may further include applying metal connecting lines to the surface before applying the thermo-resistive coating to form electrical contacts for the thermo-resistive heating plate.
  • applying the thermo-resistive coating includes depositing the thermo-resistive coating on the substrate, and curing the thermo-resistive coating.
  • the thermo-resistive coating may include single walled or multi-walled carbon nanotubes dispersed in a coating matrix.
  • a heating appliance for cooking food such as a microwave oven or a combination oven having at least a microwave heat source, includes a cooking chamber defined by cavity walls in a housing. At least one of the cavity walls defines a respective opening, with a thermo-resistive heating plate disposed therein.
  • the thermo-resistive heating plate includes a thermo-resistive coating disposed on a substrate, with the substrate being microwave transmissive to emit microwave radiation from the microwave heat source into the cooking chamber.
  • the substrate is also heat conductive to allow for the thermo-resistive coating to generate heat for heating the cooking chamber.
  • the thermo-resistive heating plate may be positioned within one or more of the cavity walls, and may include an insulation layer sandwiching the thermo-resistive coating between the insulation layer and the substrate to protect the housing.
  • the microwave heating appliance 100 includes a housing 110 with interior side walls 112, a base 111, and a ceiling 113 which cooperate to define a cooking chamber 120.
  • the housing 110 also has an outer surface 116 exposed to the external environment.
  • the heating appliance 100 includes a door 114 having an open position for providing access to the cooking chamber 120, and a closed position sealing the cooking chamber 120 from the external environment.
  • the cooking chamber 120 is sized based on suitable sizes for kitchen appliances and for receiving food items to be cooked, and may include components for optimizing space and cooking of the food items, such as a turntable (not shown) or shelving racks (not shown).
  • the microwave heating appliance 100 may draw power from an external power source (not shown) such as an electrical plug and outlet connection.
  • the heating appliance 100 may be connected to the power supply via any suitable power cable, and may include any other components such as, but not limited to, power inverters, transformers, voltage converters, etc., to supply the requisite power to features of the heating appliance 100.
  • the input may be any suitable input based on the appliance 100. For example, the voltage input may be 120 V and the maximum power may be 1600 W.
  • the microwave heating appliance 100 includes at least one heating mechanism (not shown) for cooking food placed within the cooking chamber 120.
  • the heating mechanism is activated by user input at a control panel 118 located on the outer surface 116 (as shown in FIG. 1 ) or the door 114 (not shown).
  • the heating mechanism may be included within the housing 110 or within the cooking chamber 120, as dependent on the particular type of heating appliance 100.
  • the heating mechanism may be via microwave radiation from any suitable microwave generating mechanism, such as, but not limited to, or one or more magnetrons or solid-state devices.
  • the heating appliance 100 may be referred to as microwave oven 100, and a microwave oven is depicted in FIG.
  • heating appliance 100 this is not intended to be limiting and other types of heating appliances such as combination ovens that include a microwave generating mechanism for microwave heating along with another heating mechanism (e.g., electric coils and/or gas) are also contemplated as the heating appliance 100.
  • the heating appliance 100 may be any suitable domestic appliance for cooking food, such as, but not limited to, ovens, microwave ovens, toaster ovens, and the like, such that the features described herein for the heating appliance 100 are suitable for oven or microwave oven applications where microwaves are present within the cooking chamber 120.
  • the heating appliance 100 may be any suitable domestic appliance for cooking food, such as, but not limited to, ovens, microwave ovens, toaster ovens, and the like, such that the features described herein for the heating appliance 100 are suitable for oven or microwave oven applications where microwaves are present within the cooking chamber 120.
  • the heating appliance 100 is a microwave such that the heating mechanism may be a microwave generating device disposed in the housing 110 in any suitable manner, e.g., between the side walls 112, the ceiling 113, or the base 111 and the outer surface 116.
  • the microwave radiation is generated by the microwave generating device and transmitted via any suitable mechanism, such as a waveguide, a coaxial cable or a strip line which supplies the microwave radiation to one or multiple feeding ports (as dependent on the design) which are open to the cooking chamber 120 to heat food placed therein.
  • the microwave heating appliance 100 includes one or more thermo-resistive heating plates 200 incorporated into at least a portion of one or more corresponding surfaces forming the cooking chamber 120, such as for example the base 111 (as shown schematically in FIG. 1 ), the interior side walls 112 (as shown in FIGS. 3A-B ), and/or the ceiling 113 (as shown in FIG. 4 ), or combinations thereof, hereinafter collectively referred to as cavity wall(s) 130.
  • the heating plate 200 may be incorporated as at least a portion of one or more of the cavity walls 130 (e.g., at least a portion of one or more of interior walls 112, ceiling 113, or the base 111).
  • the cavity walls 130 may be metal walls.
  • thermo-resistive heating plate 200 is incorporated into a corresponding opening 135 defined in the corresponding cavity wall 130 of the cooking chamber 120 (e.g., the base 111 in FIG. 1 , portions of the side walls 112 in FIGS. 3A-B , and the ceiling 113 in FIG. 4 ).
  • the thermo-resistive heating plate 200 is positioned within the opening 135 of the cavity wall 130 such that the thermo-resistive plate 200 is flush with cavity wall 130.
  • the thermo-resistive plate 200 may be removable from the opening 135 such that the thermo-resistive plate 200 can be easily replaced and/or serviced.
  • the thermo-resistive heating plate 200 provides an efficient heating function for convective heating for the cooking chamber 120 while also providing a microwave transmissive wall for microwave heating.
  • the thermo-resistive heating plate 200 includes a substrate 210 having an inner surface 212 facing the cooking chamber 120, and a bottom surface 214 on a bottom side of the substrate 210, opposite from the inner surface 212.
  • the thermo-resistive heating plate 200 further includes a thermo-resistive coating 220 disposed on the bottom surface 214 of the substrate 210, and an insulation layer 230 disposed on the thermo-resistive coating 220, sandwiching the thermo-resistive coating 220 between the insulation layer 230 and the substrate 210.
  • the substrate 210 may be any suitable material resistant to thermal shock and having a melting point higher than the working temperatures reached by the thermo-resistive coating 220.
  • the substrate 210 may be a glass, ceramic, glass-ceramic, or metal material.
  • the substrate 210 may be any suitable material, including, but not limited to glasses (e.g., sodalime, borosilicate, silica, etc.), glass ceramics (e.g., lithium aluminum silicates, etc.).
  • the substrate 210 may be a glass or glass-ceramic material which is colored, tinted, or transparent as based on aesthetic considerations.
  • the substrate material is selected to withstand temperatures up to 700°C without expansion or detriment to structural integrity, and may have a thermal expansion coefficient of 0.5 to 0 up to 700°C.
  • the substrate 210 may be a suitable material having a sufficient thermal conductivity for transferring heat through the substrate material and into the cooking chamber 120 as generated by the thermo-resistive coating 220 (located on the outer side as compared to the cooking chamber 120).
  • the thermal conductivity is at least 0.5 W/mK for heating the cooking chamber 120.
  • the substrate material has a thermal conductivity of 1 to 2 W/mK.
  • the substrate 210 may have any suitable thickness for transferring heat to the cooking chamber 120 and form at least a portion of a cavity wall 130, and in some embodiments, may have a thickness of 1 to 8 mm, in other embodiments 2 to 7 mm, and in yet other embodiments 2.5 to 6.5 mm.
  • the substrate 210 may be 3 to 4 mm thick.
  • the substrate 210 is at least partially transparent to microwave wavelengths through a thickness of the substrate 210 such that the microwave generating device can pass microwave radiation through the glass substrate 210 and to the cooking chamber 120, thus allowing the thermo-resistive heating plate 200 as entry point for microwave emission into the cooking chamber 120.
  • the substrate 210 may have a microwave transmittance of 30 to 75% in some embodiments, 40 to 70% in other embodiments, and 45 to 60% in yet further embodiments.
  • thermo-resistive coating 220 is coated on the bottom surface 214 of the substrate 210, and exhibits a thermo-resistive property upon application of current through the thermo-resistive coating 220.
  • the thermo-resistive coating 220 may include conductive filler particles (e.g., metal oxide particles, or graphite or carbon nanomaterials such as nanotubes, spheres, or flakes) dispersed in a ceramic matrix (e.g., alumina, silica, phosphate, etc., with the conductive filler particles being the active material for heating.
  • the thermo-resistive coating 220 may also include, in certain embodiments, other fillers such as thickeners or dispersants for aiding in deposition or film formation, such as, for example, silica.
  • the thermo-resistive coating 220 is sandwiched between the substrate 210 and an insulation layer 230.
  • the thermo-resistive coating 220 may be electrically connected in any suitable manner generally shown as electrical connection 225 in FIG. 2 , such as, but not limited to, by silver paste, copper connectors or other wiring, buses, or interconnects to flow current through the thermo-resistive coating 220 to produce heat.
  • the electrical connections 225 are positioned on opposite sides of the thermo-resistive heating plate 200 to allow current to flow through the heating plate 200 from one of the electrical connection points 225 to the other, such that heat is generated in the thermo-resistive coating 220 and transferred to the cooking chamber 120 via the substrate 210.
  • the electrical connection 225 may be sandwiched between the substrate 210 and the insulation layer 230, and be positioned on either side of the thermo-resistive coating 220 to allow current to flow therethrough.
  • the thermo-resistive coating 220 includes a coating matrix with an active filler dispersed therein to provide resistive heating to the cooking chamber 120 through the substrate 210.
  • the active filler within the thermo-resistive coating 220 behave as ohmic resistors which generate heat upon application of electricity to the thermo-resistive heating plate 200, thus providing heat to be conducted through the glass-ceramic substrate 110 to the cookware articles thereon.
  • the active filler may be, in certain embodiments, single walled or multi-walled carbon nanotubes, graphite particles, or metal oxide particles.
  • the active filler in certain embodiments, have a loading concentration of 0.001 to 30% by weight, in other embodiments 0.01 to 10% by weight, and in yet further embodiments, 0.10 to 5.0% by weight, as based on the wet loading in the coating for deposition.
  • the active filler may have each an average size (as based on the largest dimension of the particle), in some embodiments, of 0.2 nm to 300 microns, in other embodiments, 5 nm to 250 microns, and in yet other embodiments, 25 nm to 200 microns.
  • the thermo-resistive coating 220 may include, in some embodiments, other fillers in the coating matrix, such as, but not limited to, volume fillers, corrosion inhibitors, and the like, including, but not limited to, silica particles.
  • the coating matrix of the thermo-resistive coating 220 is a ceramic matrix with shielding action against oxidation at high temperatures (i.e., up to 500 degrees C), such as, but not limited to, aluminum phosphate, silicon phosphate, magnesium phosphate, silicates, or combinations thereof.
  • the pH of the liquid state of the coating matrix may be from 2 to 8.
  • the thermo-resistive coating 220 may have any suitable resistance based on its composition for the desired heat generation as based on the heating requirements for the cooking chamber 120.
  • the thermo-resistive coating 220 may have a resistance of 10 to 50 ⁇ , in other embodiments, 1.0 to 35 ⁇ , and in yet other embodiments, 20 to 30 ⁇ .
  • the thermo-resistive coating 220 upon application of current, may in certain embodiments, reach a maximum temperature of around 400°C to 600°C, in other embodiments, 450°C to 550°C, and in yet other embodiments, 475°C to 525°C.
  • the heating ramp for the thermo-resistive coating may be 45 to 250°C per minute, in other embodiment 50 to 200 °C per minute, and in yet other embodiments, 55 to 150°C per minute. Furthermore, the heating ramp for the thermo-resistive coating may be, in certain embodiments, 75 to 250°C per minute, in other embodiment 85 to 200 °C per minute, and in yet other embodiments, 95 to 150°C per minute.
  • the thermo-resistive coating 220 may be coated on the bottom surface 214 in any suitable pattern, on at least a portion of the bottom surface 214 (e.g., symmetrical or asymmetrical patterns, like stripes, checker-board pattern, segments, etc.).
  • thermo-resistive coating 220 can provide tailored heating as based on the cooking chamber 120.
  • the thermo-resistive coating 220 may be, in some embodiments, a thin film layer, such that the scale of the thermo-resistive film layer upon curing has a thickness of up to 100 micrometers. In other embodiments, the thickness of the thermo-resistive coating 220 may be thicker than those defined as thin film layers, and may have thicknesses up to the mm range.
  • the thermo-resistive coating 220 has a thickness of, in some embodiments, 15 nm to 1.75 mm, in other embodiments, 20 nm to 1.5 mm, and in yet other embodiments, 25 nm to 1 mm.
  • the thermo-resistive coating 220 may have a thickness of 25 to 500 nm, in yet other embodiments 25 to 450 nm, and in yet other embodiments, 25 to 425 nm. In at least one embodiment, after deposition, the wet thermo-resistive coating may have a thickness of 25 to 75 microns, and in other embodiments, 40 to 60 microns. In at least one embodiment, after curing, the dry thermo-resistive coating 220 has a thickness of 10 to 50 microns, in other embodiments, 15 to 45 microns, and in yet other embodiments 20 to 40 microns. Although shown in FIG.
  • the thermo-resistive coating 220 may include any number of layers to generate the desired heating, and depiction of a single layer is not intended to be limiting.
  • the thermo-resistive coating 220 may include two or more layers forming the thickness of the thermo-resistive coating.
  • each layer of the thermo-resistive coating 220 may independently be a thin film having a thickness of up to 100 microns, or have a thickness up to 1.75 mm.
  • the collective layers of the thermo-resistive coating 220 may have a thickness of up to 1.75 mm, with each layer having a varying thickness.
  • thermo-resistive coating 220 is reflective to microwave radiation, thus avoiding indirect and unwanted heat generation in the heating plate 200 when the heating appliance is operating only with microwave heating.
  • the microwave efficiency of waves passing through the coated substrate i.e., the thermo-resistive heating plate 200
  • the thermo-resistive coating 220 has a low to no absorbance of microwave radiation, and is thus reflective.
  • the thermo-resistive coating 220 alone may be 95 to 100% reflective to microwave radiation, in other embodiments 96 to 100% reflective, and in yet other embodiments 97 to 100% reflective.
  • thermo-resistive coating 220 in some embodiments has an absorptivity to microwaves of 0 to 5%, in other embodiments, 0 to 2.5%, and in yet other embodiments, 0 to 1%.
  • the absorptivity of the thermo-resistive coating 220 is the measure of a materials' effectiveness in absorbing radiant energy.
  • the substrate 210 is more transmissive for microwaves than the thermo-resistive coating 220, thus allowing the microwave emission to be directed to the cooking chamber 120.
  • the insulation layer 230 is a coating matrix material that insulates the housing 110 of the appliance 100 from heat generated by the thermo-resistive heating plate 200 as well as provides electrical insulation to the coating 220.
  • the insulation layer 230 may be chosen based on the substrate type.
  • the insulation layer 230 may be a material similar to the ceramic material of the coating matrix.
  • the material of the insulation layer 230 may be another ceramic (alumina, alumina-titania, corierite), or may be a high temperature resistant resin, such as a silicon-based high temperature resistant resin.
  • the insulation layer 230 may include any suitable number of protective and/or insulative layers and/or a combination of layer materials to sandwich the thermo-resistive coating 220 between the insulation layer 230 and the substrate 210.
  • the insulation layer 230 facilitates heat transfer in the direction of the substrate 210.
  • the insulation layer 230 may be any suitable thickness to protect the thermo-resistive coating 220 on the bottom side (with respect to the substrate 210 being on the top side) and protect the housing 110 of the appliance from heat, and in some embodiments may be 0.1 to 0.5 mm thick, in other embodiments, may be 0.25 to 0.45 mm thick, and in yet other embodiments may be 0.3 to 0.4 mm thick.
  • thermo-resistive heating plate 200 may optionally include other coatings on the inner surface 212 of the substrate 210 towards the cooking chamber 120.
  • the substrate 210 includes an easy-to-clean coating 240 on the inner surface 212 having hydrophobic or oleophobic properties (e.g., a water or oil contact angle of at least 90 degrees) such that adhesion of foodstuffs or chemicals is reduced on the easy-to-clean coating 240.
  • thermo-resistive heating plate 200 may be incorporated in other cavity walls 130, or in any combination of cavity walls 130. Moreover, the thermo-resistive heating plate 200 may be incorporated in a portion of the respective cavity wall 130. For example, the thermo-resistive heating plate 200 may form 30 to 100% of the cavity wall 130, in some embodiments, 50 to 95% of the wall 130 in other embodiments, and 75 to 90% of the wall in yet other embodiments. Referring to FIGS. 3A-B , the thermo-resistive heating plate 200 is included in the side walls 112 ( FIG. 3A ) and over a portion of the height of the side walls 112 ( FIG.
  • thermo-resistive heating plate 200 may be incorporated as at least a portion of the ceiling 113.
  • thermo-resistive heating plate 200 there may be a thermo-resistive heating plate 200 on one or more of the cavity walls 130, and depiction of the thermo-resistive heating plate 200 being incorporated in a particular location is not intended to be limiting.
  • thermo-resistive heating plate 200 generates heat via a thin film thermo-resistive heating which allows the heating plate 200 to reach high temperatures in short timespans, while avoiding microwave absorption to ensure efficient heating of the food within the cooking chamber 120.
  • a method of forming a heating appliance with a thermo-resistive heating plate includes preparing a thermo-resistive heating plate by depositing metal connecting lines on a substrate.
  • the depositing may be by any suitable method, including, but not limited to, thermal spray or screen printing.
  • the depositing may be based on a desired pattern formed.
  • the metal connecting lines may be formed using a silver paste or a silver-copper paste.
  • the method includes curing the metal connecting lines at a temperature between 50 and 500 degrees C, in some embodiments, and between 100 and 350 degrees C in other embodiments.
  • the method further includes applying a thermo-resistive coating to a bottom surface of the substrate, and curing the coating.
  • the applying may be based on the pattern of the metal connecting lines, which connect the thermo-resistive coating to a power supply.
  • the thermo-resistive coating may be applied by any suitable method, including, but not limited to, screen printing, stencil printing, or other deposition method.
  • the coating may be cured, in at least one embodiment, at a temperature between 200 and 500 degrees C, and in other embodiments, at a temperature between 300 and 400 degrees C.
  • the curing may be, in some embodiments, for 1 to 70 minutes, and in other embodiments, 20 to 35 minutes, in an oven or furnace.
  • both the metal connecting lines and the thermo-resistive coating may be applied prior to the curing step, such that the curing step may be a single step after the coating deposition.
  • thermo-resistive heating plate is then deposited within an opening in a cavity wall of the heating appliance, with the top surface of the substrate (opposite from the bottom surface) is flush with the cavity wall.
  • a heating appliance is provided that allows thermo-resistive heating of the cooking chamber via the thermo-resistive coating and heat conduction through the substrate, as well as microwave emission through the substrate into the cooking chamber via microwave transmissivity of the substrate material.
  • a heating appliance includes a thermo-resistive heating plate embedded in an opening in at least one wall defining the cooking chamber to generate heat via a thin film thermo-resistive heating which allows the heating plate to reach high temperatures in short timespans, while avoiding microwave absorption to ensure efficient heating of the food within the cooking chamber.
  • the thermo-resistive heating plate includes a substrate with a top surface facing the cooking chamber, the substrate being transmissive to microwave emission to allow microwaves to pass therethrough and thermally conductive to allow heat to transfer therethrough.
  • the bottom surface of the glass-ceramic substrate is coated with a thermo-resistive heating coating which is electrically connected to a power supply.
  • thermo-resistive coating Upon application of an electric current, the resistive property of thermo-resistive coating generates heat to be conducted through the glass-ceramic substrate to the cooking chamber.
  • the heating appliance may include an insulation layer on the surface of the thermo-resistive coating opposite to the glass-ceramic substrate to improve the heating in the direction of the glass-ceramic substrate.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Electric Ovens (AREA)
  • Ceramic Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Constitution Of High-Frequency Heating (AREA)
  • Electric Stoves And Ranges (AREA)
EP22210948.0A 2021-12-08 2022-12-01 Thermoresistive heizplatte für mikrowellengerät Withdrawn EP4195877A1 (de)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202111489849.6A CN116249235A (zh) 2021-12-08 2021-12-08 用于微波器具的热阻加热板

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EP4195877A1 true EP4195877A1 (de) 2023-06-14

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EP22210948.0A Withdrawn EP4195877A1 (de) 2021-12-08 2022-12-01 Thermoresistive heizplatte für mikrowellengerät

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US (1) US12588115B2 (de)
EP (1) EP4195877A1 (de)
CN (1) CN116249235A (de)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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